Lumbar discal cyst followed by intervertebral disc herniation: MRI findings of two cases page 1
Lumbar discal cyst followed by intervertebral disc herniation: MRI findings of two cases page 2
Lumbar discal cyst followed by intervertebral disc herniation: MRI findings of two cases page 3
Lumbar discal cyst followed by intervertebral disc herniation: MRI findings of two cases page 4

Lumbar discal cyst followed by intervertebral disc herniation: MRI findings of two cases

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  • J Orthop Sci (2006) 11:8184DOI 10.1007/s00776-005-0961-1

    Case report

    Lumbar discal cyst followed by intervertebral disc herniation:MRI findings of two cases

    Masako Tokunaga1, Toshimi Aizawa2, Hironori Hyodo1, Hirotoshi Sasaki1, Yasuhisa Tanaka2,and Tetsuro Sato1

    1 Department of Orthopaedic Surgery, Sendai Orthopaedic Hospital, 24 Izai aza Higashi-tori, Wakabayashi-ku, Sendai 984-0038, Japan2 Department of Orthopaedic Surgery, Tohoku University School of Medicine, Sendai, Japan

    medial thigh. The MRI findings 10 days after the onsetwere consistent with intervertebral disc herniation atthe L3/4 level that had spread to the L3 vertebral bodyon the right; an extradural mass of isointensity signal onT1-weighted images (T1WI) and mixed iso- and highintensities on T2-weighted images (T2WI) was seen.Its periphery was enhanced by gadolinium-diethylenetriamine-pentaacetic acid (Gd-DTPA) (Fig.1). The MRI revealed that the L3/4 intervertebral dischad mild degeneration. Conservative treatment re-lieved the patients symptoms.

    At 54 days after the onset, MRI showed that thecranial part of the extradural mass had changed tohomogenously high signal intensity on T2WI (Fig. 2).His symptoms worsened again, and MRI 90 days afterthe onset showed that the whole extradural mass was ofisointensity on T1WI and homogenously high intensityon T2WI (Fig. 3A,B). Discography (Fig. 3C) followedby computed tomography (CT) at the L3/4 level showedthat contrast medium flowed into the extradural mass.These radiological findings indicated that he had anintervertebral discal cyst at the L3/4 level.

    Right L3 hemilaminectomy was performed, and atwo-compartment cyst was found tightly adherent toboth the dura mater and the L3 and L4 nerve.Hemorrhage was encountered when ablation of the cystfrom the surrounding extradural tissues was attempted,although the exact bleeding point could not beconfirmed. The cyst contained bloody serous fluid. Itwas removed en bloc with part of the posterior annulusof the intervertebral disc. The patient experienced adramatic resolution of symptoms with quadriceps femo-ris of grade 5 on the MMT scale.

    Case 2

    A 13-year-old boy came to our hospital in July 2002because of an approximately 2-month course of lowback pain and numbness of the lateral right leg. His

    Introduction

    Several kinds of intraspinal cyst, such as the perineuralcyst,1 sacral cyst,1 synovial cyst,2 extradural ganglioncyst,3,4 and cyst of the ligamentum flavum,5 as well aspremembranous hematomas6 and intraspinal gas,7,8

    cause symptoms and signs resembling those of lumbardisc herniation.9,10 In 1997 in Japanese and in 2001 inEnglish, Toyama et al.11 and Chiba et al.9 first describedcysts with distinct connections to the intervertebral discand named them lumbar discal cysts. Several possiblecauses of these cysts can be suggested: a simple variantof normal disc degeneration,12 resorption of preexistingherniation, hematoma associated with disc prolapse,and mucoid degeneration as in a ganglion cyst.9 How-ever, the pathogenesis of discal cyst is uncertain.

    Here, we report two cases of lumbar discal cyst.From magnetic resonance image (MRI) findings, weconfirmed that the discal cyst could have developedfrom the absorption process of an intervertebral discherniation. Our patients or the family were informedthat the data concerning the cases would be submittedfor publication.

    Case reports

    Case 1

    A 38-year-old man developed acute low back pain andweakness of the right lower extremity in January 2001.Neurologically, right L3 or L4 radiculopathy was indi-cated; slight weakness (grade 4) on the manual muscletest (MMT) scale was detected in the quadriceps femo-ris, and there was sensory disturbance on the anterior to

    Offprint requests to: T. SatoReceived: January 24, 2005 / Accepted: August 29, 2005

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  • 82 M. Tokunaga et al.: Discal cyst followed by herniation

    condition was diagnosed as right L5 radiculopathy witha positive straight leg raising test (SLRT) at 20 andMMT grade 4 weakness of the extensor hallucis longusmuscle. MRI findings were consistent with interverte-bral disc herniation at L4/5, with an extradural mass ofisointensity on T1WI and low intensity on T2WI; it washeterogeneously enhanced by Gd-DTPA (Fig. 4). TheL4/5 intervertebral disc appeared to have mild degen-eration. His symptoms were not alleviated by conserva-tive treatment. One month later, the mass showedisointensity on T1WI and uniformly high intensity onT2WI (Fig. 5A,B). Discography and CT revealed around mass connected to the L4/5 disc cavity in theextradural space (Fig. 5C,D). His condition was thendiagnosed as an intervertebral discal cyst at the L4/5level.

    Fenestration of the right L4/5 was performed. A darkred cyst was identified in the right extradural space,continuous with the intervertebral disc and adherent tothe L5 nerve root. We needled the cyst wall and aspi-rated about 2ml of pure blood. A transligamentous her-niation was also detected at the cranial portion of the

    cyst. Both the cyst and herniated mass were carefullyremoved. His condition completely disappeared.

    Histology

    In both cases, the cyst wall on pathologic microscopicexamination was composed of fibrous tissue withneovascularity and hemosiderin deposits. No epitheliallini